The outstanding binding, insulating, and waterproofing characteristics of asphalt have led to its widespread utilization in a wide variety of applications including paving, roofing, weather sealing, waterproofing, and polymer modification. For instance, asphalt is used in manufacturing roofing shingles because it has the ability to bind sand, aggregate, and fillers to the roofing shingle while simultaneously providing excellent water barrier characteristics. Asphalt compositions are additionally used as processing aids for plastics.
For hundreds of years, naturally occurring asphalts have been used in numerous applications. However, today virtually all of the asphalt used in industrial applications is recovered from petroleum refining. Asphalt, or asphalt flux, is essentially the residue that remains after gasoline, kerosene, diesel fuel, jet fuel, and other hydrocarbon fractions have been removed during the refining of crude oil. In other words, asphalt flux is the last cut from the crude oil refining process.
One age-old downside associated with using hot mix asphalt is that it produces volatile materials such as hydrocarbons, sulfides, and mercaptans which generally have strong, persistent, and unpleasant odors. These odors are frequently considered to be obnoxious by persons working with the asphalt, by residents living near areas where asphalt is manufactured or paving is being done, and in general to persons who come within close proximity to the asphalt. The intensity of the unpleasant odor associated with asphalt increases with increasing temperature. Accordingly, the odor problem associated with asphalt can be severe in cases where it is heated to an elevated temperature, such as in industrial applications.
The foul odors that accompany paving roads, driveways, and parking lots are well recognized by most people in modern society. When asphalt is used in roofing applications, such as roofing shingles, roll roofing, and built-up roofing, the asphalt is typically first heated in a vessel, such as a gas-fired roofing kettle. Asphalt compositions used in plastics modification are also typically heated to an elevated temperature in mixing and processing the polymeric formulation. As the temperature of the asphalt is increased, volatile materials, such as hydrocarbons, sulfides, and mercaptans which have strong and unpleasant odors are normally emitted into the atmosphere. The odors emitted are not only unpleasant to smell, but they may also be an irritant to workers and/or other individuals in the vicinity of the vessel or to those who come within close proximity to the hot asphalt. In extreme cases, the rank fumes from the asphalt may cause headaches and/or irritation to the eyes and mucus membranes of the nose and throat, which can result in a deterioration of worker productivity and/or an increase in the number of sick days taken by workers.
Traditional odor treating compositions act as deodorizers or masking agents, function by overwhelming the undesired odor with another odor. Such techniques, however, are poor at masking strong odors. In addition, masking does not reduce the concentration of the volatiles causing the underlying undesirable odors. Accordingly, the need for an effective technique for reducing the obnoxious odors associated with asphalt containing compositions is well recognized by industrial users of asphalt and the general public.
Compositions and odor-masking additives for reducing undesirable odors emitted from odor-causing compounds are known in the art. For instance, U.S. Pat. No. 5,271,767 discloses a composition that consists essentially of (1) liquid asphalt, hot-mix asphalt, hot-mix, or cold lay asphalt with added latex and (2) an additive that contains a citrus terpene (4-isopropyl 1-methylcyclohexene) D-limonene mixed with a vegetable oil such as cottonseed oil, soya oil, rapeseed (canola) oil, peanut oil, etc. and a silicone oil dispersant. It is taught that when 0.5-1.0 parts of the composition are mixed with 99.0-99.5 parts liquid asphalt, the resulting liquid asphalt composition is substantially free of objectionable odors.
U.S. Pat. Nos. 5,989,662 and 6,107,373 disclose methods of reducing fumes produced from a kettle of molten asphalt that includes adding about 0.25 to about 6.0% by weight of a polymer (e.g. polypropylene) to the asphalt. The polymer material preferably forms a skim or skin across substantially the entire upper surface of the asphalt. These patents teach that at least a 25% reduction of the visual opacity of the fumes, at least a 20% reduction of the hydrocarbon emissions of the fumes, and at least a 15% reduction of suspended particulate emissions of the fumes is obtained.
U.S. Pat. No. 6,461,421 discloses a composition that includes (1) an odor-emitting hydrocarbonaceous material, (2) an odor-suppressing amount of an aldehyde or a ketone, and (3) a carboxylic acid ester. The odor-emitting hydrocarbonaceous material may be any hydrocarbonaceous material that emits objectionable odors at ambient or elevated temperatures. One example of a hydrocarbonaceous material given is asphalt. It is asserted that the composition significantly reduces the odor given off by asphalt.
U.S. Pat. No. 6,488,988 discloses a method and container for reducing the fuming of asphalt in a heated vessel. Trumbore teaches that a substantially insoluble blanket material is added to the liquid asphalt to form a skim on the surface of the asphalt and reduce the fuming. Examples of blanket materials include polyurethane, polyethylene terephthalate, ground soda bottles, starch, and cellulosic materials.
U.S. Pat. No. 6,987,207 discloses a composition that includes an odor-emitting hydrocarbonaceous material and an odor-suppressing amount of an additive composition that includes (1) a soy methyl ester, (2) at least one aldehyde and/or at least one ketone, and (3) at least one carboxylic acid ester. This patent teaches that the odor-emitting hydrocarbonaceous material may be any hydrocarbonaceous material that emits objectionable odors at ambient or elevated temperatures, such as asphalt. It is asserted that the use of the additive composition may significantly reduce or eliminate the odor emitted by the hydrocarbonaceous material.
U.S. Pat. No. 7,037,955 and United States Patent Publication No. 2006/0155003 disclose methods for reducing odor in an oil based medium such as asphalt. In the disclosed methods, an essential oil is added to the oil based medium in an odor reducing amount. The essential oil may be one or more essential oils or essential oil components, and includes natural extracts of various products of aromatic plants and trees. Essential oils for use in the invention include ajowan, angelica root, angelica seed, aniseed china star, carrot seed, and fir needle, among many others. Examples of essential oil components include terpenes, alcohols, aldehydes, aromatics, phenolics, esters, terpene derivatives, non-terpene essential oil components, and terpene derivatives.
U.S. Pat. No. 7,306,666 discloses a method for reducing odor in oil based media, said method comprising mixing an odor reducing amount of an odor reducing additive with an oil based medium, wherein the odor reducing additive is a mixture of essential oils, a mixture of essential oil components, or mixtures thereof, wherein the odor reducing additive is diluted with a carrier oil, which is comprised of methyl esters of canola oil, ethyl esters of canola oil, the methyl ester of soybean oil, or a mixture thereof; and wherein the oil based medium is fuel oil, waste oil fuel oil, oil based synthetic lubricants, liquid asphalt cement, or hot mix asphalt. Some examples of odor reducing additives that can be utilized in conjunction with this method include essential oils selected from the group consisting of rosemary oil, cedarwood oil, pine needle oil, eucalyptus oil, clove oil, thyme oil, vetiver oil, vanilla oleo resin, lavender oil, and tea tree oil; terpenes selected from the group consisting of α-pinene, β-pinene, d 3 carene, dipentene, p-cymene, cineole, camphor, terpineol, bornyl acetate, cedrene, cedrol, and thymol; and other substances including limonene, pine extract and pine white oil, pinus sylvestris oil, anise seed oil, clove bud oil, aniseed oil, camphor white oil, cedarwood atlas oil, cedarwood texas oil, cedarwood virginia oil, lavandin absolute, lime distilled oil, olibanum extract, rosemary oil, sandlewood west indian oil, tocopherol alpha, and vanilla.
United States Patent Publication No. 2004/0166087 discloses the addition of two specific types of ingredients to cold or hot melt asphalt or coal tar for the dual purposes of holding, reducing or complexing the obnoxious and toxic odors from asphalt while at the same time allowing a pleasant masking fragrance to predominate. The holding agents consist of various organic compounds which can bond or complex with and effectively hold onto other molecules. Typical complexing agents include dialkylgylcol alkyl ethers and dialkylphthalates. Typical fragrances include natural and synthetic oils or extracts such as lemon oil, orange oil, peppermint, spearmint, cinnamon, bubble gum and most other common fragrances. United States Patent Publication No. 2004/0166087 specifically reveals an asphalt formulation that contains 91 weight percent hot melt asphalt, 4.5 weight percent cinnamon oil, and 4.5 weight percent diethyl phthalate.
United States Patent Publication No. 2005/0223668 discloses a faced fibrous insulation assembly that includes a fibrous blanket, a facing formed by a kraft paper sheet material, and an asphalt coating layer on the inner surface of the facing that bonds the facing to the fibrous insulation blanket. The asphalt coating layer contains an odor-reducing additive in an amount to substantially eliminate odors that would otherwise be emitted by the asphalt coating layer. It is asserted that the additive does not adversely affect the adherent qualities of the asphalt coating layer. It is disclosed that the odor-reducing additive may be essential plant oils.
United States Patent Publication No. 2009/0314184 A1 discloses a composition for reducing malodorous emissions from hydrocarbonaceous materials comprising: at least one aldehyde-containing compound having a molecular weight greater than about 100 daltons and a boiling point greater than about 375° F., said composition being free of ester-containing compounds. In one embodiment of this invention the composition further includes one or more members selected from the group consisting of ketone-containing compounds, a low fuming additives and liquid carriers. In these compositions the aldehyde-containing compound can be 2-chlorobenzaldehyde, 4-chlorobenzaldehyde, alpha-methylcinnamaldehyde, 4-anisaldehyde, epsilon-cinnamaldehyde, vertraldehyde, 4-ethoxy-3-methoxybenzaldehyde, 3-ethoxy-4-hydroxybenzaldehyde, 3-nitrobenzaldehyde, vanillin or cinnamaldehyde. The ketone-containing compound that are reported to be useful in such compositions include camphor, isophorone, isobutyrophenone, propiophenone, 4-methylacetophenone, carvone, 4-chloroacetophenone, 2-benzoylbenzoic acid, 2′-acetonaphthone, benzophenone, fluorenone, 4′-ethoxyacetophenone, 4′-chlorobenzophenone, 4-acetylbenzonitrile and 4′-hydroxyacetophenone.
United States Patent Application Publication No. 2007/0213418 discloses a compound comprising a combination of materials for manufacturing a plastic product, comprising: a blend of asphalt and resin, the asphalt being included in an amount within a range of from about 0.1% to about 40% by weight of the plastic product; and wherein the asphalt functions as at least one of (i) a colorant to change the color of the plastic product; (ii) a resin replacement to reduce the amount of resin in the plastic product, (iii) a processing aid; and (iv) an additive to increase the R-Value of a foam insulation. However, this reference does not disclose or suggest any means for mitigating the strong odor associated with the asphalt used therein.
Conventional odor treating compositions commonly act as deodorizers or masking agents, essentially overwhelming the undesirable odor with one or more desirable odors. However, these compositions do not effectively mask the odors emitted from asphalt. Thus, there remains a need in the art for a composition that effectively reduces or eliminates the odors emitted from asphalt or other hydrocarbonaceous materials without simply masking the undesirable smell, where the performance of the composition is sustainable over time, and where the composition does not pose any additional health or safety issues.